#include "apue.h"
#define BSZ 48

int main() {
    FILE *fp;
    char buf[BSZ];
    memset(buf, 'a', BSZ-2);
    buf[BSZ-2]= '\0';
    buf[BSZ-1]= 'X';
    printf("string buf: %s\n", buf);
    if ((fp= fmemopen(buf, BSZ, "w+")) == NULL)
        err_sys("fmemopen failed");
    printf("initial buffer contents: %s\n", buf);
    fprintf(fp, "hello, world");
    printf("before flush: %s\n", buf);

    fflush(fp);
    printf("after fflush: %s\n", buf);
    printf("len of string in buf = %ld\n", (long)strlen(buf));

    memset(buf, 'b', BSZ-2);
    buf[BSZ-2]= '\0';
    buf[BSZ-1]= 'X';
    fprintf(fp, "hello world");
    fseek(fp, 0, SEEK_SET);
    printf("after fseek: %s\n", buf);

    memset(buf, 'c', BSZ-2);
    buf[BSZ-2]= '\0';
    buf[BSZ-1]= 'X';
    fprintf(fp, "hello, word");
    fclose(fp);
    printf("after fclose: %s\n", buf);
    printf("len of string in buf = %ld\n", (long)strlen(buf));
}


